Articular cartilage defects in joints are a significant source of pain, have a limited ability to heal, and can lead to the development of osteoarthritis (Buckwalter and Mankin, 1998; Shelbourne et al., 2003). Surgical options for symptomatic cartilage defects include palliative, reparative, and restorative methods (Cole and Lee, 2003). However the treatment algorithm and surgical indications for each of these procedures continues to evolve (Magnussen et al., 2008; Bekkers et al., 2009). Alternative treatments have been developed using biodegradable implants intended to encourage the formation of articular cartilage within the defect site. However, these implants have mechanical properties that are continually changing and often inferior to that of the native tissue during the regeneration process (Mauck et al., 2002). Furthermore, these implants rely on a controlled and robust cellular response in order to recreate an organized tissue that looks and mechanically functions like the native articular cartilage, a goal that has thus far proven elusive in the biological environment of the defective joint.
Another method to treat this clinical problem is to use well characterized, non-biodegradable implants capable of resisting in vivo mechanical loads immediately after implantation and for the duration of the regeneration process. Non-degradable constructs should ideally: (i) integrate with adjacent tissue; (ii) transmit loads much in the way of the native tissue that the implant is intended to replace; (iii) transfer load to the underlying bone (to avoid bony resorption); (iv) resist wear; (v) not cause abrasion to opposing cartilage surfaces; and (vi) allow for easy implantation and fixation to the surrounding tissues. However, to date, such an implant has not been developed that fulfills all of these criteria.